Well I tend to think that the wookie would hold his own against the predator. Especially if the Predator underestimates the wookie's strength. 4/10 maybe.
But the Snow Creature complicates things. They are predatory, and not very smart. I think the Predator takes the Snow Creature out first and quickly. He wouldnt underestimate the Snow Creature. The snow creature, after being hurt (if not dead), would try and run and hide. Once the snow creature realized it couldnt hurt the predator easily, that leaves it back to the wookie.